It has been desired by product designers and consumers to provide sophisticated design in resin moldings. In particular, so-called jet-black resin moldings that have a bluish tint and high blackness have been desired in order to provide rich impression and high-grade texture. For example, for coatings of automobiles and the like, there has been an increasing demand to improve appearance (coating texture) that appeal to aesthetic sense not only for the purpose of protecting auto bodies and improving durability. It is necessary to improve depth, transparency, and perspective feeling in color in order to improve the coating texture. Black coatings that have feelings of jet-black and depth are strongly desired as coatings providing a rich impression.
In the techniques disclosed by Patent Literature 1 and 2, carbon black is uniformly dispersed in a resin solution or a solid resin in order to obtain jet-black resin coated products, films, and moldings. However, with the above means disclosed in Patent Literature 1 and 2, a brightness (L*) is high (gray/white), and the chromaticity (a* and b*) has positive values (+a*: red and +b*:yellow). It has thus been difficult to express jet-black such as so-called “piano black” and “lusterous black of the crow”.
A color tone of a molding that uses carbon black tends to vary according to a primary particle size of the compounded carbon black. To be more specific, when carbon black with a small primary particle size is used, a color tone with blackness and an intense red color tint can be obtained. On the contrary, when carbon black with a large primary particle size is used, a color tone that has a bluish tint and reduced blackness is obtained. As described above, in a color tone of black using carbon black, blackness and a bluish tint are in a trade-off relation. Thus, it has been difficult to reproduce a jet-black color tone that has a bluish tint and high blackness.
Patent Literature 3 suggests a coating film structure that is obtained by forming a black base color layer having a brightness of less than 0.2 and a black color clear layer containing carbon black of more than 0.1 mass % and 10 mass % or less. Patent Literature 4 discloses a resin composition containing carbon nanotube fibers in a dispersion medium as a coating composition and a black coating film that is obtained by applying and drying the coating composition, so that the black coating film contains 4.5 pts·mass of carbon nanotube fibers.
However, there has been a problem in the conventional coating film structure that it is difficult to exhibit sufficient jet-black and achieve a low brightness.